About 83 percent of China's sea areas were polluted to some extent, according to a report released Friday by the State Oceanic Administration (SOA).

The polluted areas, up from 78 percent the year before, were affected by eutrophication, a process in which water bodies receive excess nutrients that stimulate excessive plant growth such as algae and nuisance plants weeds.

It also indicated other problems, including lack of oxygen and severe reductions in water quality, fish and other animal populations.

Li Haiqing, a senior official with the SOA said the administration had called on all oceanic departments to strengthen monitoring and prevention of "red tides" and other algae blooms.

Pollutants were blamed for the cause of the red tides in which large amounts of algae kill sea life. These algae vary in colour from green to brown, but are mostly red.

China saw 68 cases of red tides last year, fewer than the 82 cases in 2007. However, they contaminated a total of 13,738 square km of sea area, up 2,128 square km from the previous year.

Last June, algae invaded the eastern coastal city of Qingdao, which hosted sailing events during the 2008 Olympics, blocking proposed sailing routes and affecting preparations for the Games.

For a month, the city government mobilized soldiers and volunteers to clear more than 1 million tons of algae, and built barriers and fences to keep it out of the sailing venue. The algae was completely cleared on Aug. 1.

While some experts said it was a result of climate change and heavy rain, environmentalists believed the algae blooms were largely due to sewage and agricultural pollutant run-off.

According to the report, marine disasters resulted in 152 people dead or missing in China last year, with direct economic losses of 20.61 billion yuan (3.03 billion US dollars). The figure in 2007 was 8.84 billion yuan. Enditem